Radio-frequency switches having silicon-on-insulator field-effect transistors with reduced linear region resistance

ABSTRACT

Disclosed are devices and methods related to radio-frequency (RF) switches having silicon-on-insulator (SOI) field-effect transistors (FETs). In some embodiments, an RF switch can include an FET with shaped source, drain, and gate selected to yield a reduced per-area value of resistance in linear operating region (Rds-on). In some implementations, a plurality of such FETs can be connected in series to allow use of SOI technology in high power RF switching applications while maintaining a relatively small die size.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/557,709 filed Nov. 9, 2011 and entitled “DEVICES AND METHODOLOGIESRELATED TO A FET-BASED RF SWITCH HAVING A REDUCED PRODUCT OF RDS-ON ANDAREA,” which is expressly incorporated by reference herein in itsentirety.

BACKGROUND

1. Field

The present disclosure generally relates to field-effect transistor(FET) structures and radio-frequency (RF) devices such as switcheshaving such FET structures.

2. Description of the Related Art

A field-effect transistor (FET) can be utilized as a switch forradio-frequency (RF) applications. FET-based switches, such assilicon-on-insulator (SOI) switches are used in, for example, antennaswitch modules and front-end modules. Such applications typicallybenefit from a SOI transistor feature of ideal or nearly idealisolation.

Typically, an SOI device is rated for only a few volts. Accordingly,several SOI switches having relatively large width/length ratio can bearranged in series to provide RF switching functionality. Such aconfiguration voltage-divides the RF signal being switched, therebymitigating breakdown concerns and improving reliability in conditionsinvolving, for example, high RF power/voltage or high voltage standingwave ratio (VSWR).

SUMMARY

In a number of implementations, the present disclosure relates to atransistor that includes a semiconductor substrate, a plurality of firstdiffusion regions formed on the semiconductor substrate, and a pluralityof second diffusion regions formed on the semiconductor substrate. Thetransistor further includes a gate layer disposed over the first andsecond diffusion regions. The gate layer defines a first opening overeach of the first diffusion regions and a second opening over each ofthe second diffusion regions. At least some of the first and secondopenings have a shape other than a rectangle.

In some embodiments, the transistor can further include a contactfeature formed on each the first and second diffusion regions. In someembodiments, the transistor can further include a first conductor thatelectrically connects the contact features on the first diffusionregions. In some embodiments, the transistor can further include asecond conductor that electrically connects the contact features on thesecond diffusion regions. The first conductor can be further connectedto a source terminal and the second conductor can be further connectedto a drain terminal.

In some embodiments, at least some of the first and second openings havea first shape defined by an outline of an elongate shape having a centerand an elongation axis along a first direction and a diamond shapehaving its center positioned approximately at the center of the elongateshape. The diamond shape can be oriented so that one set of opposingcorners are along the elongation axis and the other set of opposingcorners are substantially perpendicular to the elongation axis.

In some embodiments the elongate shape can include a rectangle havingits length along the first direction. In some embodiments, the elongateshape can include a hexagon elongated along the first direction. Theplurality of first openings having the first shape can form a firstcolumn, with the first openings in the first column being arranged alonga second direction that is approximately perpendicular to the firstdirection. The plurality of second openings having the first shape canform a second column, with the second openings in the second columnbeing arranged along the second direction and offset from the firstopenings along the first direction. The first openings of the firstcolumn and the second openings of the second column can be staggeredalong the first direction and along the second direction. Each of thefirst conductor and the second conductor can extend along the seconddirection.

In some embodiments, the transistor can further include a third columnhaving additional first openings that are staggered from the secondopenings of the second column along the first direction and the seconddirection. In some embodiments, the transistor can further include afourth column having additional second openings that are staggered fromthe first openings of the third column along the first direction and thesecond direction.

In some embodiments, a neighboring pair of first and second openings caninclude a first facing portion for the first opening and a second facingportion for the second opening. At least one of the first and secondfacing portions can have a plurality of segments that extend indifferent directions.

In some embodiments, a neighboring pair of first and second openings caninclude a first facing portion for the first opening and a second facingportion for the second opening. The first and second facing portions candefine opposing sides of a quadrilateral other than a rectangle.

In some embodiments, the transistor can be a field effect transistor(FET), with the plurality of first diffusion regions being a source ofthe FET, and the plurality of second diffusion regions being a drain ofthe FET. The FET can include an n-type FET or a p-type FET. The FET caninclude a metal-oxide-semiconductor FET (MOSFET).

In some embodiments, the transistor can further include an insulatorlayer disposed below the semiconductor substrate. The semiconductorsubstrate can include a silicon substrate so as to yield asilicon-on-insulator (SOI) structure.

In some embodiments, the shape can be dimensioned to yield a reducedvalue of Rds-on per area when compared to a transistor having a similarsized rectangular opening.

In accordance with a number of implementations, the present disclosurerelates to a method for fabricating a transistor. The method includesproviding a semiconductor substrate. The method further includes forminga plurality of first diffusion regions on the semiconductor substrate,and forming a plurality of second diffusion regions on the semiconductorsubstrate. The method further includes forming a gate layer disposedover the first and second diffusion regions. The gate layer defines afirst opening over each of the first diffusion regions and a secondopening over each of the second diffusion regions. At least some of thefirst and second openings have a shape other than a rectangle.

According to some teachings, the present disclosure relates to a maskfor fabricating a semiconductor transistor. The mask includes aplurality of features that allow formation of a gate layer over asemiconductor substrate, such that the formed gate layer defines a firstopening and a second opening, with at least some of the first and secondopenings having a shape other than a rectangle.

In a number of implementations, the present disclosure relates to asemiconductor die that includes a semiconductor substrate and aplurality of transistors implemented on the substrate. Each transistorincludes a plurality of first diffusion regions and a plurality ofsecond diffusion regions. Each transistor further includes a gate layerdisposed over the first and second diffusion regions, with the gatelayer defining a first opening over each of the first diffusion regionsand a second opening over each of the second diffusion regions. At leastsome of the first and second openings have a shape other than arectangle.

In some embodiments, the plurality of transistors can be connected inseries to form a switchable conduction path for a radio-frequency (RF)signal.

In some implementations, the present disclosure relates to asemiconductor module having a packaging substrate configured to receiveplurality of components, and a die mounted on the packaging substrate.The die includes a plurality of transistors implemented on asemiconductor substrate. Each transistor includes a plurality of firstdiffusion regions and a plurality of second diffusion regions. Eachtransistor further includes a gate layer disposed over the first andsecond diffusion regions, with the gate layer defining a first openingover each of the first diffusion regions and a second opening over eachof the second diffusion regions. At least some of the first and secondopenings have a shape other than a rectangle. The module furtherincludes a plurality of connectors configured to provide electricalconnections between the die and the packaging substrate.

In accordance with some implementations, the present disclosure relatesto a radio-frequency (RF) device having a transceiver configured toprocess RF signals, a power amplifier configured to amplify an RF signalgenerated by the transceiver, and an antenna in communication with thetransceiver and configured to facilitate transmission of the amplifiedRF signal. The RF device further includes a switching module coupled tothe power amplifier and the antenna. The switching module is configuredto route the amplified RF signal from the power amplifier to theantenna. The switching module has a switch circuit including a pluralityof transistors connected in series. Each transistor includes a pluralityof first diffusion regions and a plurality of second diffusion regions.Each transistor further includes a gate layer disposed over the firstand second diffusion regions, with the gate layer defining a firstopening over each of the first diffusion regions and a second openingover each of the second diffusion regions. At least some of the firstand second openings have a shape other than a rectangle.

In some implementations, the present disclosure relates to aradio-frequency (RF) switch that includes a semiconductor substrate andan input assembly having a plurality of source regions formed on thesemiconductor substrate, a source contact formed on each of the sourceregions, and an input conductor that electrically connects to each ofthe source contacts. The RF switch further includes an output assemblyhaving a plurality of drain regions formed on the semiconductorsubstrate, a drain contact formed on each of the drain regions, and anoutput conductor that electrically connects to each of the draincontacts. The RF switch further includes a gate layer disposed over thesource and drain regions, with the gate layer defining a first openingover each of the source regions and a second opening over each of thedrain regions. At least some of the first and second openings arearranged in a two-dimensional array.

In some embodiments, the RF switch can further include an input terminalconnected to the input conductor and an output terminal connected to theoutput conductor.

In some embodiments, each of the first and second openings can have aparallelogram shape. The first and second openings can be arranged sothat neighboring sides of a pair of openings are substantially parallel,with each of the input and output conductors extending diagonally overthe corresponding ones of the first and second openings. In someembodiments, the parallelogram shape can be a square shape such that thearray of the squares defines a waffle pattern.

In some embodiments, at least some of the first and second openings canhave a first shape defined by an outline of an elongate shape having acenter and an elongation axis along a first direction and a diamondshape having its center positioned approximately at the center of theelongate shape. The diamond shape can be oriented so that one set ofopposing corners are along the elongation axis and the other set ofopposing corners are substantially perpendicular to the elongation axis.The elongate shape can include a rectangle having its length along thefirst direction. The elongate shape can include a hexagon elongatedalong the first direction. The plurality of first openings having thefirst shape can form a first column, with the first openings in thefirst column being arranged along a second direction that isapproximately perpendicular to the first direction. The plurality ofsecond openings having the first shape can form a second column, withthe second openings in the second column being arranged along the seconddirection and offset from the first openings along the first direction.The first openings of the first column and the second openings of thesecond column can be staggered along the first direction and along thesecond direction. Each of the input conductor and the output conductorcan extend along the second direction.

In some embodiments, the RF switch can further include a third columnhaving additional first openings that are staggered from the secondopenings of the second column along the first direction and the seconddirection. In some embodiments, the RF switch can further include afourth column having additional second openings that are staggered fromthe first openings of the third column along the first direction and thesecond direction.

In some embodiments, a neighboring pair of first and second openings caninclude a first facing portion for the first opening and a second facingportion for the second opening. At least one of the first and secondfacing portions can have a plurality of segments that extend indifferent directions.

In some embodiments, a neighboring pair of first and second openings caninclude a first facing portion for the first opening and a second facingportion for the second opening. The first and second facing portions candefine opposing sides of a quadrilateral other than a rectangle.

In some embodiments, the source regions, the drain regions, and the gatecan be configured as a metal-oxide-semiconductor FET (MOSFET).

In some embodiments, the RF switch can further include an insulatorlayer disposed below the semiconductor substrate. The semiconductorsubstrate can include a silicon substrate so as to yield asilicon-on-insulator (SOI) structure.

In some embodiments, the shape can be dimensioned to yield a reducedvalue of Rds-on per area when compared to a transistor having a similarsized rectangular opening.

According to a number of implementations, the present disclosure relatesto a method for fabricating a radio-frequency (RF) switch. The methodincludes providing a semiconductor substrate, forming a plurality ofsource regions on the semiconductor substrate, and forming a pluralityof drain regions on the semiconductor substrate. The method furtherincludes forming a gate layer over the source regions and the drainregions, with the gate layer defining a first opening over each of thesource regions and a second opening over each of the drain regions. Atleast some of the first and second openings are arranged in atwo-dimensional array. The method further includes forming a contact oneach of the source and drain regions, and forming an input conductorthat electrically connects the source contacts and an output conductorthat electrically connects the drain contacts.

In accordance with a number of teachings, the present disclosure relatesto a radio-frequency (RF) switch die having a semiconductor substrateand a plurality of transistors implemented on the substrate. Eachtransistor includes a plurality of source regions and a plurality ofdrain regions. Each transistor further includes a gate layer disposedover the source and drain regions, with the gate layer defining a firstopening over each of the source regions and a second opening over eachof the drain regions. At least some of the first and second openings arearranged in a two-dimensional array. The die further includes a sourcecontact formed on each source region, and a drain contact formed on eachdrain region. The die further includes an input conductor thatelectrically connects the source contacts, and an output conductor thatelectrically connects the drain contacts.

In a number of implementations, the present disclosure relates to aradio-frequency (RF) switching module having a packaging substrateconfigured to receive plurality of components, and a die mounted on thepackaging substrate. The die has a plurality of transistors implementedon a semiconductor substrate. Each transistor includes a plurality ofsource regions and a plurality of drain regions. Each transistor furtherincludes a gate layer disposed over the source and drain regions, withthe gate layer defining a first opening over each of the source regionsand a second opening over each of the drain regions. At least some ofthe first and second openings are arranged in a two-dimensional array.Each transistor further includes a source contact formed on each sourceregion, and a drain contact formed on each drain region. The die furtherincludes an input conductor that electrically connects the sourcecontacts, and an output conductor that electrically connects the draincontacts. The module further includes a plurality of connectorsconfigured to provide electrical connections between the die and thepackaging substrate.

In some implementations, the present disclosure relates to aradio-frequency (RF) device. The RF device includes a transceiverconfigured to process RF signals, a power amplifier configured toamplify an RF signal generated by the transceiver, and an antenna incommunication with the transceiver and configured to facilitatetransmission of the amplified RF signal. The RF device further includesa switching module coupled to the power amplifier and the antenna. Theswitching module is configured to route the amplified RF signal from thepower amplifier to the antenna. The switching module has a switchcircuit including a plurality of transistors connected in series. Eachtransistor includes a plurality of source regions and a plurality ofdrain regions. Each transistor further includes a gate layer disposedover the source and drain regions, with the gate layer defining a firstopening over each of the source regions and a second opening over eachof the drain regions. At least some of the first and second openings arearranged in a two-dimensional array. Each transistor further includes asource contact formed on each source region, and a drain contact formedon each drain region. The source contacts are connected to an inputconductor for receiving the amplified RF signal, and the drain contactsare connected to an output conductor for outputting the amplified RFsignal.

In some implementations, the present disclosure relates to a switchingapparatus that includes a semiconductor substrate having a surface. Theapparatus further includes a plurality of diffusion regions formed onthe substrate so as to define one or more shapes on the surface of thesubstrate. The apparatus further includes one or more first conductorselectrically connected to selected ones of the diffusion regions, withthe one or more first conductors capable of being connected together asan input for the switching apparatus. The apparatus further includes oneor more second conductors electrically connected to remaining ones ofthe diffusion regions, with the one or more second conductors capable ofbeing connected together as an output for the switching apparatus. Atleast some of the one or more shapes associated with the one or morefirst conductors and at least some of the one or more shapes associatedwith the one or more second conductors are dimensioned so as to includea first facing portion and a second facing portion that generally faceeach other and thereby belong to a neighboring pair of diffusionregions. At least one of the first and second facing portions has aplurality of segments that extend in different directions or the firstand second facing portions define opposing sides of a quadrilateralother than a rectangle.

In some embodiments, the apparatus can further include a feature formedbetween the plurality of diffusion regions and configured to allowcontrol of flow of charge between the regions connected to the one ormore first conductors and the regions connected to the one or moresecond conductors. Such a feature can include gate feature, and theplurality of diffusion regions connected to the one or more firstconductors can correspond to a source of a field effect transistor(FET). The plurality of diffusion regions can be connected to the one ormore second conductors corresponding to a drain of the FET. Such a FETcan include an n-type FET or a p-type FET. Such a FET can include ametal-oxide-semiconductor FET (MOSFET).

In some embodiments, the apparatus can further include terminals formedon the plurality of diffusion regions so as to provide electricalconnections between the diffusion regions and their respectiveconductors. The apparatus can further include a source conductor layerconfigured to electrically connect the one or more first conductors, anda drain conductor layer configured to electrically connect the one ormore second conductors.

In some embodiments, the apparatus can further include an insulatorlayer disposed below the semiconductor substrate. Such a semiconductorsubstrate can include a silicon substrate so as to yield asilicon-on-insulator (SOI) structure.

In some embodiments, wherein the one or more shapes can include a firstcross shape associated with diffusion regions connected to the firstconductors, with the first cross shape having substantiallyperpendicular extensions along X and Y directions, and the first crossshaped diffusion regions arranged along the X direction. The one or moreshapes can further include a second cross shape associated withdiffusion regions connected to the second conductors, with the secondcross shape having substantially perpendicular extensions along the Xand Y directions, and the second cross shaped diffusion regions arrangedalong the X direction and offset along the X direction from the firstcross shaped diffusion regions.

In some embodiments, the one or more shapes can further include a squareshape associated with diffusion regions connected to the secondconductors, with the square shape having sides along the X and Ydirections, and the square shaped diffusion regions arranged along the Xdirection and offset along the X direction from the first cross shapeddiffusion regions. The one or more first cross shape can further includea diamond shape at the center of the first cross shape.

In some embodiments, the first cross shape can include beveled cornersat the ends of the extensions. The one or more shapes can furtherinclude a snowflake shape associated with diffusion regions connected tothe second conductors, with the snowflake shape having a perimeterdefined by a combination of first and second squares, and the firstsquare having sides along the X and Y directions, and the second squarerotated by about 45 degrees relative to the first square.

In some embodiments, the one or more shapes associated with diffusionregions connected to the first conductors can include a first hexagonalshape, and the one or more first hexagonal shaped diffusion regions canbe arranged along an X direction. The one or more shapes associated withdiffusion regions connected to the second conductors can include asecond hexagonal shape, and the one or more second hexagonal shapeddiffusion regions can be arranged along the X direction and offset alongthe X direction from the first hexagonal shaped diffusion regions.

In some embodiments, the one or more shapes can include a firstdouble-diamond shape associated with diffusion regions connected to thefirst conductors, and the first double-diamond shape having first andsecond rhombus shapes can be joined along an X direction. The one ormore first double-diamond shaped diffusion regions can be arranged in azigzag pattern along the x direction. The one or more shapes can includea second double-diamond shape associated with diffusion regionsconnected to the second conductors, and the second double-diamond shapehaving first and second rhombus shapes can be joined along a Ydirection. The one or more second double-diamond shaped diffusionregions can be arranged in a zigzag pattern along the X direction suchthat along a given X line.

In some embodiments, the one or more shapes can include a firstdouble-diamond shape associated with diffusion regions connected to thefirst conductors, and the first double-diamond shape having first andsecond rhombus shapes can be joined along a direction at an angle ofabout 45 degrees from an X direction. The one or more firstdouble-diamond shaped diffusion regions can be arranged along the Xdirection. The one or more shapes can include a second double-diamondshape associated with diffusion regions connected to the secondconductors, and the second double-diamond shape having first and secondrhombus shapes can be joined along a direction at an angle of about 45degrees from the X direction. The one or more second double-diamondshaped diffusion regions can be arranged along the X direction andoffset along the X direction from the first double-diamond shapeddiffusion regions.

In some embodiments, the one or more shapes can include a firsthexagonal shape associated with diffusion regions connected to the firstconductors, with the first hexagonal shape stretched along a Ydirection, and the one or more first hexagonal shaped diffusion regionscan be arranged along an X direction. The one or more shapes can includea second hexagonal shape associated with diffusion regions connected tothe second conductors, with the second hexagonal shape stretched alongthe Y direction, and the one or more second hexagonal shaped diffusionregions can be arranged along the X direction and offset along the Xdirection from the first hexagonal shaped diffusion regions. The one ormore shapes can further include a diamond shape at the center of each ofthe first and second hexagonal shapes. Each of the first and secondhexagonal shapes can include tapered corners of the diamond shape alongthe X direction. The one or more shapes can further include a secondstretched hexagonal shape at the center of each of the first and secondstretched hexagonal shapes and having a Y dimension between those of therespective stretched hexagonal shape and its corresponding diamondshape.

In some embodiments, the one or more shapes can include a firstrectangular shape associated with diffusion regions connected to thefirst conductors, with the first rectangular shape stretched along a Ydirection, and the one or more first rectangular shaped diffusionregions can be arranged along an X direction. The one or more shapes caninclude a second rectangular shape associated with diffusion regionsconnected to the second conductors, with the second rectangular shapestretched along the Y direction, and the one or more second rectangularshaped diffusion regions can be arranged along the X direction andoffset along the X direction from the first rectangular shaped diffusionregions. The one or more shapes can further include a diamond shape atthe center of each of the first and second stretched rectangular shapes.

In some embodiments, the one or more shapes can include a first crossshape associated with diffusion regions connected to the firstconductors, with the first cross shape having substantiallyperpendicular extensions along directions that are about 45 degreesrelative to X and Y directions, and the one or more first cross shapeddiffusion regions can be arranged along the X direction. The one or moreshapes can include a second cross shape associated with diffusionregions connected to the second conductors, with the second cross shapehaving substantially perpendicular extensions along directions that areabout 45 degrees relative to the X and Y directions, and the one or moresecond cross shaped diffusion regions can be arranged along the Xdirection and offset along the X direction from the first cross shapeddiffusion regions. Each of the first and second cross shapes can bedimensioned so that the two extensions from a center of the shape alonga given 45 degree direction are offset on opposite sides along the 45degree line. Each offset extension can include a beveled end corner onthe side of the extension further away from the 45 degree line. Each ofthe first and second cross shapes can further include a diamond shapeabout a center of each cross shape.

In some embodiments, the one or more shapes can include an octagonalshape associated with diffusion regions connected to the firstconductors, and the one or more octagonal shaped diffusion regions canbe arranged along an X direction. The octagonal shape can include afirst stretched octagonal shape, with the first stretched direction atan angle of about 45 degrees relative to the X direction. The one ormore shapes can include a second stretched octagonal shape associatedwith diffusion regions connected to the second conductors, with thestretched direction being at an angle of about 45 degrees relative tothe X direction, and the one or more second stretched octagonal shapeddiffusion regions can be arranged along the X direction and offset alongthe X direction from the first stretched octagonal shaped diffusionregions.

According to a number of implementations, the present disclosure relatesto a radio-frequency (RF) switching device having a plurality oftransistor switches arranged in series. Each switch has an input and anoutput such that an output of an intermediate switch acts as an input ofits neighboring switch. Each switch includes a feature configured toallow control of flow of charge between the input and the output. Eachswitch further includes a semiconductor substrate having a surface; aplurality of diffusion regions formed on the substrate so as to defineone or more shapes on the surface of the substrate; one or more firstconductors electrically connected to selected ones of the diffusionregions, with the one or more first conductors capable of beingconnected together as an input for the switching apparatus; and one ormore second conductors electrically connected to remaining ones of thediffusion regions, with the one or more second conductors capable ofbeing connected together as an output for the switching apparatus. Atleast some of the one or more shapes associated with the one or morefirst conductors and at least some of the one or more shapes associatedwith the one or more second conductors are dimensioned so as to includea first facing portion and a second facing portion that generally faceeach other and thereby belong to a neighboring pair of diffusionregions. At least one of the first and second facing portions has aplurality of segments that extend in different directions or the firstand second facing portions define opposing sides of a quadrilateralother than a rectangle.

In some embodiments, the semiconductor substrate can include a siliconsubstrate. The RF switching device can further include an insulatorlayer below the silicon substrate so as to yield a silicon-on-insulator(SOI) structure so as to provide high isolation and high R_(ON)/C_(OFF)figure of merit. Each transistor switch can include a MOSFET switch suchthat the input includes a source. The feature for controlling the flowof charge can include a gate, and the output can include a drain. Thenumber of switches can be selected so as to allow voltage division ofhigh power RF signals, with each divided voltage being selected to beless than a breakdown voltage of the SOI structure. Dimensions andarrangement of the first and second facing portions can be selected soas to yield a relatively low product of R_(DS-ON) and area of eachswitch.

In accordance with some embodiments, the present disclosure relates toan antenna switch module for a wireless device. The module includes aswitching device configured to switch one or more RF signals to and fromone or more antennas. The switching device includes a plurality oftransistor switches, with each switch having an input and an output suchthat an output of an intermediate switch acts as an input of itsneighboring switch, and each switch including a feature configured toallow control of flow of charge between the input and the output. Eachswitch further includes a semiconductor substrate having a surface; aplurality of diffusion regions formed on the substrate so as to defineone or more shapes on the surface of the substrate; one or more firstconductors electrically connected to selected ones of the diffusionregions, with the one or more first conductors capable of beingconnected together as an input for the switching apparatus; and one ormore second conductors electrically connected to remaining ones of thediffusion regions, with the one or more second conductors capable ofbeing connected together as an output for the switching apparatus. Atleast some of the one or more shapes associated with the one or morefirst conductors and at least some of the one or more shapes associatedwith the one or more second conductors are dimensioned so as to includea first facing portion and a second facing portion that generally faceeach other and thereby belong to a neighboring pair of diffusionregions. At least one of the first and second facing portions has aplurality of segments that extend in different directions or the firstand second facing portions define opposing sides of a quadrilateralother than a rectangle. The module further includes one or more antennaports configured to allow connections to the one or more antennas. Themodule further includes one or more RF ports configured to allow routingof the one or more RF signals to and/or from the one or more antennas.

In a number of embodiments, the present disclosure relates to afront-end module for a wireless device. The module includes a switchingdevice configured to switch one or more RF signals to and from one ormore antennas, with the switching device including a plurality oftransistor switches, and each switch having an input and an output suchthat an output of an intermediate switch acts as an input of itsneighboring switch. Each switch includes a feature configured to allowcontrol of flow of charge between the input and the output. Each switchfurther includes a semiconductor substrate having a surface; a pluralityof diffusion regions formed on the substrate so as to define one or moreshapes on the surface of the substrate; one or more first conductorselectrically connected to selected ones of the diffusion regions, withthe one or more first conductors capable of being connected together asan input for the switching apparatus; and one or more second conductorselectrically connected to remaining ones of the diffusion regions, withthe one or more second conductors capable of being connected together asan output for the switching apparatus. At least some of the one or moreshapes associated with the one or more first conductors and at leastsome of the one or more shapes associated with the one or more secondconductors are dimensioned so as to include a first facing portion and asecond facing portion that generally face each other and thereby belongto a neighboring pair of diffusion regions. At least one of the firstand second facing portions has a plurality of segments that extend indifferent directions or the first and second facing portions defineopposing sides of a quadrilateral other than a rectangle. The modulefurther includes one or more input RF ports configured to receive andprovide the one or more RF signals to the switching device. The modulefurther includes one or more output RF ports configured to receive anoutput RF signal from the switching device and route the output RFsignal to a desired destination.

According to a number of embodiments, the present disclosure relates toa wireless device having a transceiver configured to process received anRF signal and transmit an RF signal. The wireless device furtherincludes an antenna configured to facilitate receiving of the receivedRF signal and transmission of the transmit signal. The wireless devicefurther includes at least one switching module configured to allowrouting of a desired RF signal between the transceiver and the antenna.The switching device has one or more inputs and one or more outputs. Theswitching device further includes one or more MOSFET SOI transistorswitches arranged in series, with each switch including one or morediffusion regions having a first shape on the surface of the substrateand one or more diffusion regions having a second shape on the surfaceof the substrate. The first and second shapes are dimensioned so as toinclude first and second facing portions that generally face each other.At least one of the first and second facing portions has a plurality ofsegments that extend in different directions or the first and secondfacing portions define opposing sides of a quadrilateral other than arectangle. The switching device further includes one or more sourceconductors that interconnect the one or more first shaped diffusionregions and one or more drain connectors that interconnect the one ormore second shaped diffusion regions. The MOSFET SOI transistor switchescan be configured so as to provide high isolation and highR_(ON)/C_(OFF) figure of merit. The first and second shapes of thediffusion regions can be selected so as to yield a relatively lowproduct of R_(DS-ON) and area of the switching module.

In some implementations, the present disclosure relates to a method forfabricating a radio-frequency (RF) switching device. The method includesproviding or forming a silicon-on-insulator (SOI) structure having anisolated well on an insulator layer. The method further includes formingone or more source regions and one or more drain regions in the well,with the one or more source regions including a first shape, and the oneor more drain regions including a second shape. The first and secondshapes are dimensioned so as to include first and second facing portionsthat generally face each other. At least one of the first and secondfacing portions has a plurality of segments that extend in differentdirections or the first and second facing portions define opposing sidesof a quadrilateral other than a rectangle. The method further includesforming a gate between the one or more source regions and the one ormore drain regions. The method further includes forming one or moreelectrical conductors that interconnect each of the one or more sourceregions. The method further includes forming one or more electricalconductors that interconnect each of the one or more drain regions.

In some implementations, the present disclosure relates to aradio-frequency (RF) switch having a semiconductor substrate and adiffusion layer formed on the substrate. The RF switch further includesa gate layer formed on the diffusion layer. The gate layer defines aplurality of shaped openings arranged in a two-dimensional manner andexposes opening-shaped regions of the diffusion layer. Each of theopening-shaped regions is grouped as either a source region or a drainregion. The RF switch further includes an electrical contact formed oneach of the opening-shaped regions. The RF switch further includes oneor more source conductors configured to electrically connect theelectrical contacts associated with the source regions, and one or moredrain conductors configured to electrically connect the electricalcontacts associated with the drain regions.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

The present disclosure relates to U.S. patent application Ser. No.13/672,410, titled “DEVICES AND METHODS RELATED TO FIELD-EFFECTTRANSISTOR STRUCTURES FOR RADIO-FREQUENCY APPLICATIONS” filed on evendate herewith and hereby incorporated by reference herein in itsentirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A schematically depicts a wireless device having a switchingcomponent that can be configured to include one or more features of thepresent disclosure.

FIG. 1B schematically depicts a more specific example of the wirelessdevice of FIG. 1A.

FIG. 2A schematically depicts a switching module that can be configuredto include one or more features of the present disclosure.

FIG. 2B shows a plan view of a more specific example of the switchingmodule of FIG. 2A.

FIG. 2C shows a side view of the switching module of FIG. 2B.

FIG. 3 schematically depicts a die having a switch array that can beconfigured to include one or more features of the present disclosure.

FIG. 4 shows an example of a switch array having a plurality of fieldeffect transistors (FETs) along a given switch arm.

FIG. 5 shows that in some implementations, RF switches having one ormore features of the present disclosure can be in a N-pole-M-throwconfiguration.

FIGS. 6A and 6B show plan and sectional views of an examplesilicon-on-insulator (SOI) metal-oxide-semiconductor FET (MOSFET) devicehaving a finger configuration.

FIGS. 7A and 7B show plan and sectional views of an example array of SOIMOSFET devices having a multiple-finger configuration.

FIGS. 8A and 8B show an example array of diamond shaped FET devicesarranged in a waffle configuration.

FIG. 9 shows an example array of hexagonal shaped FET devices.

FIG. 10 shows an example array of octagonal shaped FET devices.

FIG. 11 shows an example array of double-diamond shaped FET devices.

FIG. 12 shows an example of a variation of the array of FIG. 11.

FIG. 13 shows an example array of cross shaped FET devices.

FIG. 14 shows an example array of cross shaped FET devices and diamondshaped FET devices.

FIG. 15 shows an example array of cross shaped FET devices and starshaped FET devices.

FIG. 16 show an example array of modified-star shaped FET devices.

FIG. 17 shows an example array of FET devices having a combination ofrectangle and diamond shapes.

FIG. 18A shows an example array of FET devices having a shape that is avariation of the example shape of FIG. 17.

FIG. 18B shows an example of how edges and/or corners of the examplearray of FIG. 18A can be configured.

FIG. 19 shows an example array of FET devices having a shape that is avariation of the example shape of FIG. 18.

FIG. 20 shows an example of a metal interconnect configuration forinterconnecting source and drain regions of an array of FET devices.

FIG. 21 shows an example of a variation of the configuration of FIG. 20.

FIG. 22 shows an electric potential contour pattern between source anddrain of a rectangular shaped FET device.

FIG. 23 shows an electric potential contour pattern between source anddrain of a diamond shaped FET device.

FIG. 24 shows a process that can be implemented to fabricate one or moreFET devices having one or more features as described herein.

FIG. 25 shows various stages of fabrication associated with the processof FIG. 24.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

Disclosed herein are devices and method related to semiconductortransistors having one or more desirable performance features. Suchtransistors are described herein in the context of field effecttransistors (FETs) implemented as silicon-on-insulator (SOI) devices. Itwill be understood, however, that one or more features of the presentdisclosure can also be implemented in other types of transistors and/orother process technologies. For example, bipolar junction transistors(BJTs) can be configured to include one or more features of the presentdisclosure. In another example, transistors associated with non-SOIprocess technologies can be configured to include one or more featuresof the present disclosure.

Various examples of FETs are described herein in the context ofswitching of radio-frequency (RF) signals. It will be understood,however, that one or more features of the present disclosure can also beimplemented in other types of applications.

FIG. 1A shows that in some embodiments, one or more features of thepresent disclosure can be implemented in a wireless device 100 such as acellular phone, smart phone, tablet, or any other portable deviceconfigured for voice and/or data communication. The wireless device 100is depicted as including a battery 102 or a receptacle for receiving abattery. Such a battery can provide power to a number of othercomponents in the wireless device 100.

The wireless device 100 is depicted as further including a component 104configured to generate transmit signals and/or process received signals.In some embodiments, such transmission and reception functionalities canbe implemented in separate components (e.g., a transmit module andreceiving module), or be implemented in a same module (e.g., atransceiver module).

In some embodiments, one or more features of the present disclosure canbe implemented in devices configured to perform both transmission andreception of RF signals (e.g., a wireless transceiver), in devicesconfigured to receive only (e.g., a wireless receiver), or in devicesconfigured to transmit only (e.g., a wireless transmitter).

The wireless device 100 is depicted as further including a switchcomponent 106. Such a component can include, for example, an antennaswitch module and/or a front-end module. In some embodiments, one ormore features associated with FET switches as described herein can beimplemented in the switch component 106.

The wireless device 100 is depicted as further including an antennacomponent 108. Such a component can include one or more antennas tofacilitate transmission and/or reception of RF signals.

FIG. 1B shows a more specific example of how the wireless device 100 ofFIG. 1A can be implemented. In FIG. 1B, an example wireless device 100shown to include one or more switches having configurations as describedherein. For example, a switch 106 can be configured to provide switchingbetween, for example, different bands and/or modes, transmit and receivemodes, etc.

In the example wireless device 100, a power amplifier (PA) module 96having a plurality of PAs can provide an amplified RF signal to theswitch 106 (via a duplexer 93), and the switch 106 can route theamplified RF signal to an antenna 108. The PA module 96 can receive anunamplified RF signal from a transceiver 104 that can be configured andoperated in known manners. The transceiver 104 can also be configured toprocess received signals. The transceiver 104 is shown to interact witha baseband sub-system 93 that is configured to provide conversionbetween data and/or voice signals suitable for a user and RF signalssuitable for the transceiver 104. The transceiver 104 is also shown tobe connected to a power management component 92 that is configured tomanage power for the operation of the wireless device 100. Such a powermanagement component can also control operations of the basebandsub-system 93 and other components of the wireless device 100.

The baseband sub-system 93 is shown to be connected to a user interface90 to facilitate various input and output of voice and/or data providedto and received from the user. The baseband sub-system 93 can also beconnected to a memory 91 that is configured to store data and/orinstructions to facilitate the operation of the wireless device, and/orto provide storage of information for the user.

In some embodiments, the duplexer 94 can allow transmit and receiveoperations to be performed simultaneously using a common antenna (e.g.,108). In FIG. 1B, received signals are shown to be routed to “Rx” paths(not shown) that can include, for example, a low-noise amplifier (LNA).

The example duplexer 94 is typically utilized for frequency-divisionduplexing (FDD) operation. It will be understood that other types ofduplexing configurations can also be implemented. For example, awireless device having a time-division duplexing (TDD) configuration caninclude respective low-pass filters (LPF) instead of the duplexers, andthe switch (e.g., 106 in FIG. 1B) can be configured to provide bandselection functionality, as well as Tx/Rx (TR) switching functionality.

A number of other wireless device configurations can utilize one or morefeatures described herein. For example, a wireless device does not needto be a multi-band device. In another example, a wireless device caninclude additional antennas such as diversity antenna, and additionalconnectivity features such as Wi-Fi, Bluetooth, and GPS.

FIG. 2A shows that in some embodiments, one or more features of thepresent disclosure can be implemented in a module such as a switchingmodule 110. Such a module can be implemented as, for example, the switchcomponent 106 described in reference to FIGS. 1A and 1B.

In FIG. 2A, the switching module 110 is depicted as including a die 112,a connectivity component 114, and a packaging component 116. The die 112can include one or more FETs having one or more features as describedherein. The connectivity component 114 can include parts and/orstructures such as connectors and terminals that allow transfer ofsignals to and from the die 112 and transfer of power to circuits on thedie 112. The packaging component 116 can include parts and/or structuresthat provide, for example, mounting substrate and protection of the die112.

FIGS. 2B and 2C show a plan view and a side view of a module 110 thatcan be a more specific example of the module 110 of FIG. 2A. The examplemodule 110 can include a packaging substrate 81 that is configured toreceive a plurality of components. In some embodiments, such componentscan include a die 112 having one or more featured as described herein.For example, the die 112 can include a switch circuit 106 having one ormore features described herein. A plurality of connection pads 84 canfacilitate electrical connections such as wirebonds 83 to connectionpads 82 on the substrate 81 to facilitate passing of various signals toand from the die 112.

In some embodiments, the components mounted on the packaging substrate81 or formed on or in the packaging substrate 81 can further include,for example, one or more surface mount devices (SMDs) (e.g., 87) and oneor more matching networks (e.g., 86). In some embodiments, the packagingsubstrate 81 can include a laminate substrate.

In some embodiments, the module 110 can also include one or morepackaging structures to, for example, provide protection and facilitateeasier handling of the module 110. Such a packaging structure caninclude an overmold 88 formed over the packaging substrate 81 anddimensioned to substantially encapsulate the various circuits andcomponents thereon.

It will be understood that although the module 110 is described in thecontext of wirebond-based electrical connections, one or more featuresof the present disclosure can also be implemented in other packagingconfigurations, including flip-chip configurations.

FIG. 3 shows that in some implementations, a die 120 (such as the die112 of FIG. 2) can include one or more integrated circuits (ICs). Forexample, a transceiver 122 can be provided on the die 120, along with apower amplifier 124 and a switch array 126. Such functional componentscan be implemented as separate ICs, in a single IC, or some combinationthereof. In some embodiments, the switch array 126 can include one ormore FETs having one or more features as described herein.

FIG. 4 schematically depicts an example of an RF transistor switchingarray 130 in which FETs having one or more features as described hereincan be implemented. An array 134 of transistors 146 indicated as aseries arm can be provided between an RF port 132 and an antenna port138. In some embodiments, an array 140 of transistors 146 indicated as ashunt arm can also be provided between the RF port 132 and a commonground 144.

The RF port 132 can include a dedicated transmission (TX) port, adedicated receive (RX) port, a transmit/receive (TRX) port, or awide-band (WB) port. For the TX example, the RF port 132 can beconnected to an output of a power amplifier. For the RX example, the RFport 132 can be connected to a filter which in turn can be connected toan ADC for baseband processing. For the TRX and WB examples, the RF port132 can be connected to respective input(s) and output(s) forbidirectional passage of RF signals. The antenna port 138 can beconnected to one or more antennas.

As shown in FIG. 4, a series gate control 136 and a shunt gate control142 can be coupled to their respective arrays so as to provide controlsignals that either switch ON or OFF the series or shunt transistorstacks, respectively. When the RF port 132 is to be connected to theantenna port 138, a series gate control signal can be asserted, and ashunt gate control signal can be de-asserted. On the other hand, when itis desirable to close the RF port 132 from the antenna port 138 andprovide electrical isolation, the series gate control signal can bede-asserted, and the shunt gate control signal can be asserted. Thepresence of such a shunt arm and the shunt gate control can be optionalfor an RF switch, and can provide greater isolation when the RF switchis in an OFF state.

In the example RF transistor switching array 130 of FIG. 4, resistorscan be provided between the transistors 146 and the gate control (136 or142) so as to provide isolation between relatively high RF voltagesfound at the transistors 146 and relatively low voltage control logic orlevel shifters that drive the switch arms. In some embodiments,additional RC filtering can be provided in the control circuitry so asto further knock down high RF voltages.

In the example RF transistor switching array 130 of FIG. 4, the bodyconnection in each transistor switch is depicted as being unconnected.Such a body connection can be configured in a number of ways, including,for example, a floating body, a dynamic (active) bias, and a diode bias.

In the example configuration of FIG. 4, the FET devices are arranged inseries. In some implementations, FET devices having one or more featuresas described herein can be arranged in other configurations. Forexample, such FET devices can be implemented in an N-pole-M-throwswitch. FIG. 5 shows an example 150 of such a switch having a singlepole (e.g., for an antenna port 158) and ten throws (e.g., for TX, RXand wide-band channels 152). For such an example with ten channels,switches 154 (indicated as WB1, WB2, WB3, WB4, WB5, WB6, RX2, RX1, TX2and TX1) can include FETs. In the example shown, the wide-band channelsand the RX channels can be provided with additional enable switches 156so as to provide improved isolation between channels. Such additionalenable switches can also include FETs.

As described in reference to FIGS. 4 and 5, switching of RF signals caninvolve many FET-based switches. In the context of SOI(silicon-on-insulator) process technology, FET devices can provideadvantages such as improved isolation between adjacent devices due to aninsulator below each device. Such improved isolation can result in, forexample, lower parasitic capacitance which can improve power consumptionat a given performance level, as well as resistance to latchup.Accordingly, SOI transistors are finding more and more applications ashigh-frequency RF switches.

In the context of SOI devices where breakdown voltages can be relativelylow, a switching device can include a plurality of SOI FET switchesarranged in series to provide a functionality of a single RF switch byvoltage-dividing an RF signal. Such a configuration can allow switchingof high power RF signals or switching under high VSWR (voltage standingwave ratio) conditions. Accordingly, the number of SOI FET devices canincrease.

In some SOI FET configurations, each transistor can be configured as afinger-based device where source and drain are rectangular shaped (in aplan view) and a gate structure extends between the source and the drainlike a rectangular shaped finger. FIGS. 6A and 6B show plan and sidesectional views of an example finger-based FET device implemented as anSOI configuration. As shown, FET devices described herein can include ap-type FET or an n-type FET. Thus, although some FET devices aredescribed herein as p-type devices, it will be understood that variousconcepts associated with such p-type devices can also apply to n-typedevices.

As shown in FIGS. 6A and 6B, a pMOSFET can include an insulator layerformed on a semiconductor substrate. The insulator layer can be formedfrom materials such as silicon dioxide or sapphire. An n-well is shownto be formed in the insulator such that the exposed surface generallydefines a rectangular region. Source (S) and drain (D) are shown to bep-doped regions whose exposed surfaces generally define rectangles. Asshown, S/D regions can be configured so that source and drainfunctionalities are reversed.

FIGS. 6A and 6B further show that a gate (G) can be formed on the n-wellso as to be positioned between the source and the drain. The gate isdepicted as having a rectangular shape that extends along with thesource and the drain. Also shown is an n-type body contact. Formationsof the rectangular shaped well, source and drain regions, and the bodycontact can be achieved by a number of known techniques. Further,operation of such MOSFET devices can be performed in a number of knownmanners.

FIGS. 7A and 7B show plan and side sectional views of an example of amultiple-finger FET device implemented on SOI. Formations of rectangularshaped n-well, rectangular shaped p-doped regions, rectangular shapedgates, and n-type body contact can be achieved in manners similar tothose described in reference to FIGS. 6A and 6B.

The example multiple-finger FET device of FIGS. 7A and 7B can be made tooperate such that a drain of one FET acts as a source of its neighboringFET. Thus, the multiple-finger FET device as a whole can provide thevoltage-dividing functionality described in reference to FIG. 4. Forexample, an RF signal can be provided at one of the outermost p-dopedregions (e.g., the leftmost p-doped region); and as the signal passesthrough the series of FETs, the signal's voltage can be divided amongthe FETs. In such an example, the rightmost p-doped region can act as anoverall drain of the multi-finger FET device.

The example rectangular shaped configurations of FIGS. 6 and 7 typicallyyield a relatively high Rds-on (resistance in the linear operatingregion) for a given area associated with the device. To reduce Rds-on, aFET device can be made to be larger which in turn can undesirablyincrease the size of a die on which many such FET devices are formed. Inthe context of increased number of SOI FET devices, such an increase insizes of the FET devices and the die are generally undesirable.

Disclosed herein are a number of non-limiting examples of how FETdevices can be configured to provide advantageous features that includereduced Rds-on per area of FETs. Such a feature can also be expressed asa product of Rds-on and area of a FET.

FIG. 8A shows a plan view of a configuration 200 where a plurality ofimplant/diffusion regions are indicated as 202 and 212. As describedherein, such regions can be n-doped or p-doped. In the context of SOIprocess technology, such regions can be formed in a well (p-well orn-well) (not shown) which is formed on an insulator (not shown). In thisexample configuration, each of the diffusion regions 202, 212 has aright-angle rhombus shape (also referred to herein as a diamond shape)relative to the direction of conductors 206 and 216. The diamond shapeddiffusion regions are arranged so that the sides of two neighboringregions face each other substantially squarely, resulting in a wafflelike arrangement.

The example configuration 200 is shown to include a gate material 210formed between the diffusion regions 202, 212. In this particularexample, a single gate structure having openings for the diffusionregions 202, 212 can be provided to turn on or off flow of chargebetween the diffusion regions at the same time. Such a gateconfiguration can be implemented in, for example, the voltage-dividingseries of transistors described in reference to FIG. 7. In otherembodiments, different gates can be provided so as to allow separatecontrol of groups of diffusion regions.

The example configuration 200 is shown to include an electrical contactstructure 204, 214 on each of the diffusion regions 202, 212. Such acontact structure can include, for example, a pad and/or a via. Thecontact structures 204, 214 are shown to be electrically connected ingroups by the conductors 206, 216.

In this particular example, the conductors 206, 216 are configured toextend along the X direction, diagonally through the opposing corners ofthe diamonds. In some embodiments, the example device 200 can beconfigured as a single FET device with every other conductorrepresenting a source (or a drain) and the other conductors representinga drain (or a source) of the single FET device. In such an embodiment, aplurality of such source/drain regions can be connected in parallel. Forexample, if the first conductor 206 is a source, then all of thediffusion region(s) connected to it can act as source region(s). Then,the second conductor 216 and its connected diffusion regions can act asa drain. Thus, the third, fifth and seventh conductors and theirrespective diffusion regions can act as sources connected in parallel tothe first conductor. Likewise, the fourth, sixth and eighth conductorsand their respective diffusion regions can act as drains connected inparallel to the second conductor. In some embodiments, such an assemblyof sources and drains connected in parallel and providing a single FETfunctionality can be utilized as one stage of an RF switch having aplurality of stages. Such plurality of stages can include a plurality ofsimilarly configured FETs, or a combination of differently configuredFETs.

In some embodiments, the example device 200 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 206 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 216 and its connected diffusion regions can act as adrain relative to the first conductor 206. Likewise, the secondconductor 216 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

In some implementations, the diamond shaped diffusion regions arrangedin the waffle configuration can yield an RF switch having a reduced(Rds-on) (area) product when compared to a rectangular fingerconfiguration. An example of such a reduction is described herein ingreater detail.

FIG. 8A further shows that a given diamond shaped diffusion regionincludes a portion of its boundary that generally faces a neighboringdiffusion region belonging to an adjacent source or drain. For example,an area 218 includes sides of two neighboring diffusion regions(belonging to respective source and drain groups) that generally faceeach other.

FIG. 8B shows an isolated view of such two neighboring diffusionregions. In this example, the two neighboring diffusion regions areindicated as 212 and 202. The diffusion region 212 includes a side 232that generally faces a side 222 belonging to the diffusion region 202.In this particular example of the diamond shaped diffusion regionsarranged in a waffle configuration, the two facing sides of neighboringdiffusion regions are opposing sides of a rectangle.

As described herein, there are other shapes of diffusion regions and/orarrangements of such diffusion regions that can provide improvedperformance such as greater reductions in (Rds-on)(area) products.Various non-limiting examples described in reference to FIGS. 9-19include various shaped implant diffusion regions that can be n-doped orp-doped. In the context of SOI process technology, such regions can beformed in a well (p-well or n-well) (not shown) which is formed on aninsulator (not shown). In some implementations, such diffusion regionsarranged in various configurations can yield RF switches having reduced(Rds-on)(area) products when compared to, for example, a rectangularfinger configuration and/or a diamond/waffle configuration example ofFIG. 8.

In the examples shown in FIGS. 9-19, a gate material is provided foreach example configuration. Such a gate material is shown to be formedas a single structure between diffusion regions so as to allow turningon or off flow of charge between the diffusion regions at the same time.It will be understood that such a gate configuration can be implementedin, for example, the voltage-dividing series of transistors described inreference to FIG. 7. In other embodiments, different gates can beprovided so as to allow separate control of groups of diffusion regions.

FIG. 9 shows a plan view of a configuration 300 having a plurality ofimplant/diffusion regions indicated as 302 and 312. In this exampleconfiguration, each of the diffusion regions 302, 312 has a hexagonalshape. In some embodiments, such hexagonal shapes can be stretched alonga direction of conductors 306 and 316. As shown, the hexagonal shapeddiffusion regions can be arranged so that the sides of two neighboringregions face each other as indicated by 318. In this particular example,such facing-sides are depicted as being opposite sides of anon-rectangular parallelogram.

The example configuration 300 is shown to include a gate material 310formed between the diffusion regions 302, 312. Further, the exampleconfiguration 300 is shown to include electrical contact structures 304on each of the diffusion regions 302, and electrical contact structures314 on each of the diffusion regions 312. In other embodiments, eachdiffusion region can include greater or lesser number of such electricalcontact structures. Such contact structures can include, for example, apad and/or a via. The contact structures 304, 314 are shown to beelectrically connected in groups by the conductors 306, 316.

In this particular example, the conductors 306, 316 are configured toextend along the X direction, along the elongation direction of thehexagonal shapes. In some embodiments, the example device 300 can beconfigured as a single FET device with every other conductorrepresenting a source (or a drain) and the other conductors representinga drain (or a source) of the single FET device. In such an embodiment, aplurality of such source/drain regions can be connected in parallel. Forexample, if the first conductor 306 is a source, then all of thediffusion regions connected to it can act as source regions. Then, thesecond conductor 316 and its connected diffusion regions can act as adrain. Thus, the third, fifth and other odd-numbered conductors andtheir respective diffusion regions can act as sources connected inparallel to the first conductor. Likewise, the fourth, sixth and othereven-numbered conductors and their respective diffusion regions can actas drains connected in parallel to the second conductor. In someembodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 300 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 306 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 316 and its connected diffusion regions can act as adrain relative to the first conductor 306. Likewise, the secondconductor 316 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 10 shows a plan view of a configuration 320 having a plurality ofimplant/diffusion regions indicated as 322 and 332. In this exampleconfiguration, each of the diffusion regions 322, 332 has an octagonalshape. In some embodiments, such octagonal shapes can be stretched alonga direction, and conductors 306 and 316 can extend along a directionthat goes through opposing sides adjacent to the stretched sides of theoctagonal shapes. As shown, the octagonal shaped diffusion regions canbe arranged so that a given octagon includes two sides that face twodifferent neighboring regions. Such facing arrangements are indicated as338 a and 338 b. In this particular example, the facing sides of 338 aare depicted as being opposite sides of a rectangle, and the facingsides of 338 b are depicted as being opposite sides of a non-rectangularparallelogram.

The example configuration 320 is shown to include a gate material 330formed between the diffusion regions 322, 332. Further, the exampleconfiguration 320 is shown to include an electrical contact structure324, 334 on each of the diffusion regions 322, 332. In otherembodiments, each diffusion region can include other number of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 324, 334 are shownto be electrically connected in groups by the conductors 326, 336.

In some embodiments, the example device 320 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 326 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor336 and its connected diffusion regions can act as a drain. Thus, thethird, fifth and other odd-numbered conductors and their respectivediffusion regions can act as sources connected in parallel to the firstconductor. Likewise, the fourth, sixth and other even-numberedconductors and their respective diffusion regions can act as drainsconnected in parallel to the second conductor. In some embodiments, suchan assembly of sources and drains connected in parallel and providing asingle FET functionality can be utilized as one stage of an RF switchhaving a plurality of stages. Such plurality of stages can include aplurality of similarly configured FETs, or a combination of differentlyconfigured FETs.

In some embodiments, the example device 320 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 326 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 336 and its connected diffusion regions can act as adrain relative to the first conductor 326. Likewise, the secondconductor 336 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 11 shows a plan view of a configuration 340 having a plurality ofimplant/diffusion regions indicated as 342 and 352. In this exampleconfiguration, each of the diffusion regions 342, 352 has adouble-diamond shape that can be defined as two rhombus shapes withtheir corners overlapping. In some embodiments, such double-diamondshapes can be oriented along perpendicular directions in an alternatingmanner (e.g., along X and Y directions). For a pair of rows of suchalternating orientations, one row is offset along the X direction sothat the alternating orientations also exist along the Y direction. Inthe example shown, a conductor 346 connects X-direction-orienteddouble-diamond shapes among a pair of rows; and a conductor 356 connectsY-direction-oriented double-diamond shapes among a pair of rows. Asshown, the double-diamond shaped diffusion regions are arranged so thata given pair of X-direction and Y-direction double-diamond shapesincludes a facing area indicated as 358. In this particular example, theend corner and its adjacent sides of one double-diamond shape generallyface a joining portion of the other double-diamond shape. Accordingly,the facing area can be generally defined as being “V” shaped.

The example configuration 340 is shown to include a gate material 350formed between the diffusion regions 342, 352. Further, the exampleconfiguration 340 is shown to include an electrical contact structure344, 354 on each of the two diamonds of the double-diamond shapeddiffusion regions 342, 352. In other embodiments, each diffusion regioncan include other number of such electrical contact structures. Suchcontact structures can include, for example, a pad and/or a via. Thecontact structures 344, 354 are shown to be electrically connected ingroups by the conductors 346, 356.

In some embodiments, the example device 340 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 346 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor356 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 340 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 346 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 356 and its connected diffusion regions can act as adrain relative to the first conductor 346. Likewise, the secondconductor 356 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 12 shows a plan view of a configuration 360 having a plurality ofimplant/diffusion regions indicated as 362 and 372. In this exampleconfiguration, each of the diffusion regions 362, 372 has adouble-diamond shape similar to that of FIG. 11. In this example,however, such double-diamond shapes can be oriented so that for a groupof connected diffusion regions, a lower side adjacent to an end cornerof one region faces an upper side adjacent to an opposite end corner ofthe next diffusion region. For the next group of connected diffusionregions, such a pattern is repeated but offset so that a joiningrecessed corner of a diffusion region of the first group faces aprotruding corner between the joining corner and the end corner of adiffusion region of the second group. Accordingly, the examplearrangement yields facing areas that include those indicated as 378 aand 378 b. The facing area 378 a can include end sides that are oppositesides of a non-rectangular parallelogram. The facing area 378 b caninclude offset saw-teeth shaped sides of a pair of a pair of diffusionregions belonging to different groups, so as to yield a saw-teeth shapedfacing area.

The example configuration 360 is shown to include a gate material 370formed between the diffusion regions 362, 372. Further, the exampleconfiguration 360 is shown to include an electrical contact structure364, 374 on each of the two diamonds of the double-diamond shapeddiffusion regions 362, 372. In other embodiments, each diffusion regioncan include other number of such electrical contact structures. Suchcontact structures can include, for example, a pad and/or a via. Thecontact structures 364, 374 are shown to be electrically connected ingroups by the conductors 366, 376.

In some embodiments, the example device 360 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 366 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor376 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 360 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 366 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 376 and its connected diffusion regions can act as adrain relative to the first conductor 366. Likewise, the secondconductor 376 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 13 shows a plan view of a configuration 380 having a plurality ofimplant/diffusion regions indicated as 382 and 392. In this exampleconfiguration, each of the diffusion regions 382, 392 has a cross shape.In some embodiments, such cross shapes can be oriented so that theperpendicular extensions are directed along X and Y directions. For apair of groups of cross shaped diffusion regions along the X direction,one group is offset along the X direction so that a cross shape of onegroup is positioned about half-way (along the X direction) between twocross shapes of the other group. A pair of groups of cross shapeddiffusions along the Y direction is offset in a similar manner. In theexample shown, conductors 386 and 396 are shown to extend along the Xdirections. As shown, the cross shaped diffusion regions can be arrangedso that two neighboring regions belonging to two groups face each otheras indicated by 398. In this particular example, the lower rightrecessed corner (of one cross shape) and its adjacent sides are depictedas facing the upper left recessed corner (of the other cross shape) andits sides.

The example configuration 380 is shown to include a gate material 390formed between the diffusion regions 382, 392. Further, the exampleconfiguration 380 is shown to include electrical contact structures 384,394 on each of the diffusion regions 382, 392. In other embodiments,each diffusion region can include other numbers of such electricalcontact structures. Such contact structures can include, for example, apad and/or a via. The contact structures 384, 394 are shown to beelectrically connected in groups by the conductors 386, 396.

In this particular example, the conductors 386, 396 are configured toextend along the X direction. In some embodiments, the example device380 can be configured as a single FET device with every other conductorrepresenting a source (or a drain) and the other conductors representinga drain (or a source) of the single FET device. In such an embodiment, aplurality of such source/drain regions can be connected in parallel. Forexample, if the first conductor 386 is a source, then all of thediffusion regions connected to it can act as source regions. Then, thesecond conductor 396 and its connected diffusion regions can act as adrain. Thus, any other odd-numbered conductors and their respectivediffusion regions can act as sources connected in parallel to the firstconductor. Likewise, any other even-numbered conductors and theirrespective diffusion regions can act as drains connected in parallel tothe second conductor. In some embodiments, such an assembly of sourcesand drains connected in parallel and providing a single FETfunctionality can be utilized as one stage of an RF switch having aplurality of stages. Such plurality of stages can include a plurality ofsimilarly configured FETs, or a combination of differently configuredFETs.

In some embodiments, the example device 380 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 386 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 396 and its connected diffusion regions can act as adrain relative to the first conductor 386. Likewise, the secondconductor 396 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIGS. 14 and 15 show that in some implementations, first and secondgroups of diffusion regions corresponding to source and drain do notneed to have same shapes.

FIG. 14 shows a plan view of a configuration 400 having a plurality ofimplant/diffusion regions 402, and a plurality of implant/diffusionregions 412 having a different shape as that of the regions 402. In thisexample configuration, each of the diffusion regions 402 has a shapethat can be defined by an outline resulting from a combination of across and a commonly centered rhombus whose opposing corners extendalong the extensions of the cross. Further, each of the diffusionregions 412 has rectangular shape (e.g., a square) having sides thatextend along the perpendicular directions of the extensions of thecross. In this example configuration, the square regions 412 are offsetabout half-way between the centers of the crosses 402, such that a givensquare is approximately at a center of four neighboring crosses 402. Inthe example shown, conductors 406 are shown to extend through thecrosses 402 in a direction along one of the two perpendicular directionsassociated with the extensions of the crosses 402; and conductors 416are shown to extend through the square regions 412 in a directiongenerally parallel to that of the conductors 406. As shown, the crossshaped and square diffusion regions can be arranged so that twoneighboring regions belonging to two groups face each other as indicatedby 418. In this particular example, the inner portion of upperextensions of the cross shape 402 are depicted as facing the two loweradjacent sides of the square shape 412, so as to generally define a “V”shaped facing area.

The example configuration 400 is shown to include a gate material 410formed between the diffusion regions 402, 412. Further, the exampleconfiguration 400 is shown to include electrical contact structures 404,414 on each of the respective diffusion regions 402, 412. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 404, 414 are shownto be electrically connected in groups by the conductors 406, 416.

In some embodiments, the example device 400 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 406 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor416 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 400 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 406 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 416 and its connected diffusion regions can act as adrain relative to the first conductor 406. Likewise, the secondconductor 416 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 15 shows a plan view of a configuration 420 that is similar to theexample configuration 400 of FIG. 14. Implant/diffusion regions 422 havea cross shape that does not include the rhombus shaped center, but doesinclude beveled corners at the ends of the extensions. Implant/diffusionregions 432 have a star shape that can be defined by an outlineresulting from two co-centered squares, where one is rotated by about 45degrees. The arrangement of the diffusion regions 422 and 432 is similarto the example of FIG. 14. As shown, the cross shaped and star shapeddiffusion regions can be arranged so that two neighboring regionsbelonging to two groups face each other as indicated by 438. In thisparticular example, the inner portion of left extensions of the crossshape 422 are depicted as facing the right corner and adjacent sides ofthe star shape 432.

The example configuration 420 is shown to include a gate material 430formed between the diffusion regions 422, 432. Further, the exampleconfiguration 420 is shown to include electrical contact structures 424,434 on each of the respective diffusion regions 422, 432. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 424, 434 are shownto be electrically connected in groups by the conductors 426, 436.

In some embodiments, the example device 420 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 426 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor436 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 420 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 426 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 436 and its connected diffusion regions can act as adrain relative to the first conductor 426. Likewise, the secondconductor 436 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 16 shows a plan view of a configuration 440 where implant/diffusionregions 442, 452 have a modified cross shape. Each of the fourextensions of the cross shape is shown to be offset from theperpendicular center lines towards the clockwise side. Further theclockwise-side corner at the end of each extension is shown to include abevel. As shown, the diffusion regions 442 are arranged along a generaldirection of extension of conductors 446 that forms an angle of about 45degrees relative to two parallel extension of the cross shape. Thediffusions regions 452 are arranged and oriented similarly; and areoffset from the diffusion regions 442 so as to provide staggered centersof the two groups of regions 442, 452. As shown, the modified crossshaped diffusion regions can be arranged so that two neighboring regionsbelonging to two groups face each other as indicated by 458. In thisparticular example, edges associated with one extension of one cross isdepicted as facing a recessed portion defined by two adjacent extensionof the neighboring cross.

The example configuration 440 is shown to include a gate material 450formed between the diffusion regions 442, 452. Further, the exampleconfiguration 440 is shown to include electrical contact structures 444,454 on each of the respective diffusion regions 442, 452. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 444, 454 are shownto be electrically connected in groups by the conductors 446, 456.

In some embodiments, the example device 440 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 446 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor456 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 440 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 446 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 456 and its connected diffusion regions can act as adrain relative to the first conductor 446. Likewise, the secondconductor 456 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 17 shows a plan view of a configuration 460 where implant/diffusionregions 462, 472 include a shape that can be defined by an outline of arectangle and a generally co-centered rhombus. The rhombus is orientedso that its two opposing corners are along the length direction of therectangle. As shown, the diffusion regions 462, 472 are arranged so thatthe rectangles' length direction is along X direction. Conductors 466and 476 are shown to extend along Y direction so as to connect centersof their respective diffusion regions. The diffusions regions 462 andthe diffusion regions 472 are offset from each other so as to bestaggered with each other along both X and Y directions. As shown, thediffusion regions can be arranged so that two neighboring regionsbelonging to two groups face each other as indicated by 478. In thisparticular example, upper left edge of the rectangle and the upper leftedge of the rhombus of one region are shown to face the lower right edgeof the rectangle and the lower right edge of the rhombus of the otherregion.

The example configuration 460 is shown to include a gate material 470formed between the diffusion regions 462, 472. Further, the exampleconfiguration 460 is shown to include electrical contact structures 464,474 on each of the respective diffusion regions 462, 472. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 464, 474 are shownto be electrically connected in groups by the conductors 466, 476.

In some embodiments, the example device 460 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 466 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor476 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 460 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 466 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 476 and its connected diffusion regions can act as adrain relative to the first conductor 466. Likewise, the secondconductor 476 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 18A shows a plan view of a configuration 480 whereimplant/diffusion regions 482, 492 include a shape that can be avariation of the diffusion regions 462, 472 of FIG. 17. The corners ofthe ends of the rectangular shape are shown to be beveled so as to yieldpointed ends. As shown, the diffusion regions 482, 492 are arranged sothat their length direction is along X direction. Conductors 486 and 496are shown to extend along Y direction so as to connect centers of theirrespective diffusion regions. The diffusions regions 482 and thediffusion regions 492 are offset from each other so as to be staggeredwith each other along both X and Y directions. As shown, the diffusionregions can be arranged so that two neighboring regions belonging to twogroups face each other as indicated by 498. In this particular example,upper left edge of the rectangle and the upper left edge of the rhombusof one region are shown to face the lower right edge of the rectangleand the lower right edge of rhombus of the other region.

The example configuration 480 is shown to include a gate material 490formed between the diffusion regions 482, 492. Further, the exampleconfiguration 480 is shown to include electrical contact structures 484,494 on each of the respective diffusion regions 482, 492. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 484, 494 are shownto be electrically connected in groups by the conductors 486, 496.

In some embodiments, the example device 480 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 486 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor496 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 480 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 486 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 496 and its connected diffusion regions can act as adrain relative to the first conductor 486. Likewise, the secondconductor 496 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

FIG. 18B shows an example of how edges and corners of a FET device 480(such as the example of FIG. 18A) can be configured. In the example,implant/diffusion regions (e.g., 492) that are not along an edge aredepicted as having a similar shape as that of FIG. 18A. In someembodiments, implant/diffusion regions along an edge of the FET devicecan be shaped to retain similar facing configuration (e.g., 498 in FIG.18A) with corresponding neighboring inner implant/diffusion regions, aswell as to accommodate the edge. For example, each of the edge regions(indicated as 482′) has a right side shape similar to those of innerregions 482, and a left side shape that is squared to accommodate theleft edge of the FET device. In another example, each of the edgeregions (indicated as 482″) along the upper edge has a lower side shapesimilar to those of inner regions 482, and an upper side shape that issquared to accommodate the left edge of the FET device.

In some embodiments, implant/diffusion regions at a corner of a FETdevice can be shaped to retain similar facing configuration (e.g., 498in FIG. 18A) with one or more neighboring inner implant/diffusionregions, as well as to accommodate the corner. For example, a cornerregion (indicated as 482′″) has a lower right corner shape selected toyield the similar facing configuration as others (e.g., 498 in FIG. 18A)with one or more corresponding inner implant/diffusion regions; and theremaining portions of the corner region 482′″ are shown to accommodatethe respective edges, the respective corner, and the neighboring regions(e.g., 482′ and 482″).

As with the example configuration of FIG. 18A, an electrical contactstructure 484, 494 is shown to be disposed at each of theimplant/diffusion regions (482, 482′, 482″, 482′″, 492) in FIG. 18B.Such contact structures can include, for example, a pad and/or a via.The contact structures 484, 494 are shown to be electrically connectedin groups by the conductors 486, 496. In some embodiments, theconductors 486, 496 can be dimensioned to accommodate the shape of thecontact structures 484, 494 and/or the shape of the implant/diffusionregions. For example, the contact structures at non-corner edge regions,as well as inner regions can be shaped to accommodate the contactstructures 484, 494. In another example, the contact structure at thecorner region 482′″ can be shaped to accommodate the contact structure484 as well as the corner region 482′″.

In the example shown in FIG. 18B, the first group of conductors 486 canbe connected to a first common terminal that serves as a terminal forone of a source and a drain. In some embodiments, such a common terminal(not shown) can be formed over the gate material (e.g., along one of theedges of the FET device). Similarly, the second group of conductors 496can be connected to a second common terminal that serves as a terminalfor the other of the source and the drain. In some embodiments, such acommon terminal (not shown) can be formed over the gate material (e.g.,along one of the edges of the FET device).

In some embodiments, the body of the FET device can be floating, or canbe provided with a bias. In the example shown in FIG. 18B, the lattercan be accommodated by a connection port 488 that is connected to aplurality of contact structures 489. Such contact structures (489) canbe connected to a conductive layer (not shown) in electrical contactwith the body portion of the FET (e.g., through body contacts).

FIG. 19 shows a plan view of a configuration 500 where implant/diffusionregions 502, 512 include a shape that can be a variation of thediffusion regions 482, 492 of FIG. 18. The length-wise portion thatextends along the X direction is shown to start at a given width at thecenter, taper down to smaller-width portions, and end with opposingpointed ends. Conductors 506 and 516 are shown to extend along Ydirection so as to connect centers of their respective diffusionregions. The diffusions regions 502 and the diffusion regions 512 areoffset from each other so as to be staggered with each other along bothX and Y directions. As shown, the diffusion regions can be arranged sothat two neighboring regions belonging to two groups face each other asindicated by 518. In this particular example, upper right edges of thetapered portion and the upper right edge of the rhombus of one regionare shown to face the lower left edges of the tapered portion and thelower left edge of the rhombus of the other region.

The example configuration 500 is shown to include a gate material 510formed between the diffusion regions 502, 512. Further, the exampleconfiguration 500 is shown to include electrical contact structures 504,514 on each of the respective diffusion regions 502, 512. In otherembodiments, each diffusion region can include other numbers of suchelectrical contact structures. Such contact structures can include, forexample, a pad and/or a via. The contact structures 504, 514 are shownto be electrically connected in groups by the conductors 506, 516.

In some embodiments, the example device 500 can be configured as asingle FET device with every other conductor representing a source (or adrain) and the other conductors representing a drain (or a source) ofthe single FET device. In such an embodiment, a plurality of suchsource/drain regions can be connected in parallel. For example, if thefirst conductor 506 is a source, then all of the diffusion regionsconnected to it can act as source regions. Then, the second conductor516 and its connected diffusion regions can act as a drain. Thus, anyother odd-numbered conductors and their respective diffusion regions canact as sources connected in parallel to the first conductor. Likewise,any other even-numbered conductors and their respective diffusionregions can act as drains connected in parallel to the second conductor.In some embodiments, such an assembly of sources and drains connected inparallel and providing a single FET functionality can be utilized as onestage of an RF switch having a plurality of stages. Such plurality ofstages can include a plurality of similarly configured FETs, or acombination of differently configured FETs.

In some embodiments, the example device 500 can be configured so as toprovide a plurality of cascading stages of transistors arranged inseries. For example, if the first conductor 506 is a source, then all ofthe diffusion region(s) connected to it can act as source region(s). Thesecond conductor 516 and its connected diffusion regions can act as adrain relative to the first conductor 506. Likewise, the secondconductor 516 and the third conductor can act as source and drain,respectively, relative to each other. Such repeating source/drainconfiguration can continue as to yield a desired number of cascadingstages of transistors that can be utilized as a series of RF switches.

In some implementations, some or all of the example configurationsdescribed in reference to FIGS. 8-19 can be configured to accommodateedges and/or corners of their respective FET devices, in manners similarto the example described in reference to FIG. 18B.

FIG. 20 shows an example of how a plurality of FET devices can beconnected in an assembly so as to provide a desirable voltage dividingfunctionality. For the purpose of describing the example of FIG. 20, itis assumed that a single FET device can be configured so that everyother conductor is connected to one or more source (or drain) regionsand the other conductors connected to one or more drain (or source)regions (such as those described in reference to FIGS. 8-19), such thata plurality of such source/drain regions are electrically connected inparallel.

FIG. 20 shows an example configuration 600 where three FET devices 602,604, 606 are connected in series. Suppose that a conductive layer 610 isa source terminal for the three-FET configuration 600. Then, aconductive layer 616 can be a drain terminal. The source layer 610 canbe connected to source conductors (e.g., every other conductor strip) ofthe first FET 602 but be electrically isolated from the first FET'sdrain conductors. A conductive layer 612 can be configured to beconnected to the drain conductors of the first FTE 602 and sourceconductors of the second FET 604, but be electrically isolated from thefirst FET's source conductors and the second FET's drain conductors.Similarly, a conductive layer 614 can be configured to be connected tothe drain conductors of the second FTE 604 and source conductors of thethird FET 606, but be electrically isolated from the second FET's sourceconductors and the third FET's drain conductors. The drain layer 616 canbe connected to drain conductors of the third FET 606 but beelectrically isolated from the third FET's source conductors.

FIG. 21 shows another example of how a given FET device can beconfigured so as to provide a collective source and a collective drain.For the purpose of describing the example of FIG. 21, it is assumed thatthe FET device can be configured so that every other conductor isconnected to one or more source (or drain) regions and the otherconductors connected to one or more drain (or source) regions (such asthose described in reference to FIGS. 8-19), such that a plurality ofsuch source/drain regions are electrically connected in parallel.

FIG. 21 shows an example configuration 620 where a single FET device 630can be divided into a collective source and a collective drain. Aconductive layer 660 is shown to be connected to a source terminal 662,and a conductive layer 670 is shown to be connected to a drain terminal672. Suppose that the source layer 660 is connected to first (640) andthird (644) conductors from the left and their respective diffusionregions (650, 654) (e.g., through vias 638), but electrically isolatedfrom the second (642) and fourth (646) conductors and their respectivediffusion regions (652, 656). Then, the drain layer 670 can be connectedto the second (642) and fourth (646) conductors and their respectivediffusion regions (652, 656) (e.g., through vias 648), but electricallyisolated from the first (640) and third (644) conductors and theirrespective diffusion regions (650, 654).

As understood in the art, notable factors that contribute to Rds-on of aFET can include channel properties, contact resistance of the terminalsfor the two S/D regions, and properties associated with the two S/Dregions. Assuming that the contact resistances remain generally thesame, effects of different shapes of the S/D regions have been evaluatedfor different shapes.

A comparison of performances of a rectangular shaped source/drainconfiguration and a diamond shaped source drain configuration wereperformed. The channel component of Rds-on was numerically evaluatedwith HSpice on a simple finger-configuration (rectangular shaped) NMOSdevice. The example device had an aspect ratio W/L of about 10 μm/0.32μm. This particular example NMOS aspect ratio corresponds roughly to asingle finger of a typical RF switch TX-arm stack. A numericallycalculated value of about 2.46 Ω for Rds-on was obtained from the HSpiceevaluation, and such a value was then used to calibrate an effectivechannel doping for the device geometry using 2-D EM simulation. This canbe accomplished by running PISCES algorithm iteratively on the fingergeometry, and varying the channel doping until the cell's Rds-onapproximately matches the 2.46 Ω value. Once calibrated, thecorresponding doping level can then be used in a model for the diamondgeometry NMOS device.

The example dimensions of the foregoing rectangular and diamondgeometries (700 and 710) are shown in FIGS. 22 and 23. In FIG. 22, therectangular shaped diffusion regions are depicted as 702 and 704; andtheir dimensions and separation are shown on the scales. In FIG. 23,portions of the diamonds (712, 714) that face each other are shown; andtheir dimensions and separation are shown on the scales. In each ofFIGS. 22 and 23, the values associated with the contour scales along theright sides of the plots are electrical potential values in volts.

FIGS. 22 and 23 also show electrical potential contour plots for therectangular and diamond configurations. Such potential contour plotswere obtained by generating a PISCES geometry file (*.mesh) by anappropriated configured open-source programs such as EasyMesh. Such aprogram can partition a 2-dimensional region into an array of trianglessuch as those shown in FIGS. 22 and 23.

Based on the foregoing example analyses, the rectangular configurationyields a calculated product of Rds-on and area of about (33.8 kΩ)(0.84μm)(0.44 μm)=12.5 kΩ·μm². For the diamond configuration, such a productof Rds-on and area is calculated to be about (17.5 kΩ)(0.594 μm)(0.887μm)=9.2 kΩ·μm² which is about 26% less than that of the rectangularcase.

In some implementations, some or all of the examples described herein inreference to 9-21 can have (Rds-on)(area) products lower than both ofthe rectangular and diamond cases. Other configurations different thanthe rectangular and diamond configurations can also be provided so as toyield such desirable reduced values of (Rds-on)(area) products.

FIG. 24 shows a process 800 that can be implemented to fabricate FETstructures associated with the examples described herein. FIG. 25 showsstructures at different stages corresponding to the various steps of theprocess 800 of FIG. 24.

In block 812, an SOI structure having an isolated well of an insulatorlayer can be formed or provided, so as to yield a structure 820 wherethe well is indicated as 828 and the insulator layer is indicated as824. A substrate 822 below the insulator layer 824, as well as aninsulator 826 that isolates the well 828 are also shown.

In block 814, diffusion regions can be formed in the well, such that theregions have footprints that include facing portions that either includeat least one portion having a plurality of segments extending indifferent directions, or defining opposing sides of a non-rectangularquadrilateral. In some embodiments, such facing portions can defineopposing sides of a rectangle. Such a step can yield a structure 830having a first diffusion region 832 and a second diffusion region 834formed on the well 828. Such diffusion regions can be configured tofunction as source and drain individually or in conjunction with otherdiffusion regions.

In block 816, one or more electrical contact terminals can be formed oneach of the diffusion regions. Such a step can yield a structure 840having an electrical contact terminal 842 disposed on the firstdiffusion region 832 and an electrical contact terminal 844 disposed onthe second diffusion region 834. Such electrical contact terminals canbe connected to source and drain individually or in conjunction withother contact terminals.

Block 818 shows that in some implementations, a gate can be formedbetween the first diffusion region and the second diffusion region. Sucha step can yield a structure 850 having a gate 852 disposed on the well828 and between the first diffusion region 832 and the second diffusionregion 834.

In some implementations, various example shapes associated with thediffusion regions, gate openings, contact pads, and/or conductors can befabricated utilizing a number of process technologies. Such processtechnologies can include, for example, one or more masks having selectedshapes that facilitate process steps such as photolithographic basedsteps involving etching, masking, deposition, and the like.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While some embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A radio-frequency (RF) switch comprising: asemiconductor substrate; an input assembly including a plurality ofsource regions formed on the semiconductor substrate, a source contactformed on each of the source regions, and an input conductor thatelectrically connects to each of the source contacts; an output assemblyincluding a plurality of drain regions formed on the semiconductorsubstrate, a drain contact formed on each of the drain regions, and anoutput conductor that electrically connects to each of the draincontacts; and a gate layer disposed over the source and drain regions,the gate layer defining a first opening over each of the source regionsand a second opening over each of the drain regions, at least some ofthe first and second openings arranged in a two-dimensional array, eachof the first and second openings forming a double-diamond shapeddiffusion region, the source regions, the drain regions, and the gatelayer configured as one or more field effect transistors (FETs).
 2. TheRF switch of claim 1 further comprising an input terminal connected tothe input conductor and an output terminal connected to the outputconductor.
 3. The RF switch of claim 1 wherein at least some of thefirst openings have an elongation axis along a first direction.
 4. TheRF switch of claim 3 wherein at least some of the second openings havean elongation axis extending along a second direction approximatelyperpendicular to the first direction.
 5. The RF switch of claim 4wherein each diamond in the double-diamond of the respective first andsecond openings has its center along the elongation axis of therespective opening.
 6. The RF switch of claim 5 wherein a first group offirst openings form corners of a first zigzag extending along the firstdirection.
 7. The RF switch of claim 6 wherein a second group of secondopenings form corners of a second zigzag extending along the firstdirection, the first and second zigzags offset from one another in thesecond direction.
 8. The RF switch of claim 7 further comprising atleast one additional zigzag having additional first openings andextending along the first direction, and at least one additional zigzaghaving additional second openings and extending along the firstdirection, the additional zigzags offset from one another in the seconddirection.
 9. The RF switch of claim 7 wherein alternating corners ofthe first zigzag are aligned with alternating corners of the secondzigzag along the first direction.
 10. The RF switch of claim 4 whereineach of the input conductor and the output conductor extends along thesecond direction.
 11. The RF switch of claim 1 wherein a neighboringpair of first and second openings includes a first facing portion forthe first opening in the pair and a second facing portion for the secondopening in the pair, the first and second facing portions defining afacing area therebetween.
 12. The RF switch of claim 11 wherein thefacing area defined by the first and second facing portions of theneighboring pair of first and second openings defines a generally “V”shaped area.
 13. The RF switch of claim 1 wherein the source regions,the drain regions, and the gate are configured as ametal-oxide-semiconductor FET (MOSFET).
 14. The RF switch of claim 1further comprising an insulator layer disposed below the semiconductorsubstrate that includes a silicon substrate to yield asilicon-on-insulator (SOI) structure.
 15. The RF switch of claim 1wherein the first and second openings are dimensioned to yield a reducedvalue of Rds-on per area when compared to a transistor having similarlysized rectangular openings.
 16. The RF switch of claim 1 wherein aneighboring pair of first and second openings includes a first facingportion for the first opening in the pair and a second facing portionfor the second opening in the pair, and the first and second facingportions define a generally saw-tooth facing area therebetween.
 17. Aradio-frequency (RF) switching module, comprising: a packaging substrateconfigured to receive plurality of components; a die mounted on thepackaging substrate, the die having a plurality of transistorsimplemented on a semiconductor substrate, each transistor including aplurality of source regions and a plurality of drain regions, eachtransistor further including a gate layer disposed over the source anddrain regions, the gate layer defining a first opening over each of thesource regions and a second opening over each of the drain regions, atleast some of the first and second openings arranged in atwo-dimensional array, each of the first and second openings forming adouble-diamond shaped diffusion region, each transistor furtherincluding a source contact formed on each source region, and a draincontact formed on each drain region, the die further including an inputconductor that electrically connects the source contacts, and an outputconductor that electrically connects the drain contacts; and a pluralityof connectors configured to provide electrical connections between thedie and the packaging substrate, the source regions, the drain regions,and the gate layer configured as one or more field effect transistors(FET's).
 18. The RF switching module of claim 17 wherein a neighboringpair of first and second openings includes a first facing portion forthe first opening in the pair and a second facing portion for the secondopening in the pair, and the first and second facing portions define agenerally “V” shaped facing area therebetween.
 19. A radio-frequency(RF) device, comprising: a transceiver configured to process RF signals;a power amplifier configured to amplify an RF signal generated by thetransceiver; an antenna in communication with the transceiver andconfigured to facilitate transmission of the amplified RF signal; and aswitching module coupled to the power amplifier and the antenna, theswitching module configured to route the amplified RF signal from thepower amplifier to the antenna, the switching module having a switchcircuit including a plurality of transistors connected in series, eachtransistor including a plurality of source regions and a plurality ofdrain regions, each transistor further including a gate layer disposedover the source and drain regions, the gate layer defining a firstopening over each of the source regions and a second opening over eachof the drain regions, at least some of the first and second openingsarranged in a two-dimensional array, each of the first and secondopenings forming a double-diamond shaped diffusion region, eachtransistor further including a source contact formed on each sourceregion, and a drain contact formed on each drain region, the sourcecontacts connected to an input conductor for receiving the amplified RFsignal, the drain contacts connected to an output conductor foroutputting the amplified RF signal, the source regions, the drainregions, and the gate layer configured as one or more field effecttransistors (FET's).
 20. The RF device of claim 19 wherein the RF deviceis a portable wireless device.